PROBLEM TO BE SOLVED: To provide a digital data transmitting and receiving circuit by which two bit data are superimposed with two kinds of signals and transmitting them through a pair of transmission lines within one clock period by deforming an LVDS system and two bit data are superimposed with two kinds of signals and transmitting them through a pair of transmission lines within one clock period by deforming a TMDS system. SOLUTION: The digital data transmitting and receiving circuit includes a first current source, a second current source in which the presence or the absence of the current supply is controlled by the state of a low-order bit of input data a transmitting terminal which is linked to a node, where the first and the second current sources are met, and is constituted of a transistor circuit that determines the transmission path of the current of the two current sources by the state of high-order bit of the input data, a transmission line which is provided to transmit signals of the transmitting terminal, a terminating resistor which is linked to the transmission line and an output detecting circuit which is used to detect output data from the voltage being applied to the terminating resistor. COPYRIGHT: (C)2004,JPO